The doctrine of mutually assured destruction proposes an incredibly high-stakes test of the power of deterrence. In the Cold War, deterrence prevailed. The coming Republican presidential primary is a decidedly lower-stakes affair, but it, too, may pit two political superpowers against each other in a contest where all-out war would destroy them both.

The problem for those two would-be candidates, Jeb Bush and Mitt Romney, is that a Cold War-like equilibrium can’t hold for very long in a multi-candidate, winner-take-all primary. One of them must eventually abandon the field, and the longer it takes to determine whom, the greater the risk grows either that an insurgent will eclipse both of them or that bombs will start dropping. Romney in particular understands the importance of vanquishing rivals and consolidating the establishment vote—if he hadn’t done this early, and to great effect, in 2012, he probably would have lost the primary. The problem he faces now is that Bush will probably have more money at his disposal than anyone he’s ever defeated.

It is with this war-game scenario in mind that Bush and Romney are scheduled to meet in Utah this week—presumably in the hope of avoiding an outcome in which both men have exhausted extensive resources and the only beneficiary is someone neither of them wants atop the Republican ticket.

The problem becomes all the more confounding when you account for the fact that both will want the other to do the gracious thing and bow out. Assuming neither of them does, the $64,000 question is, Who’s more vulnerable in a Bush-Romney slugfest?

I’ve considered the question carefully, and, for the following reasons, concluded that Romney has a significantly stronger hand.

1) Romney goes in with a pretty big polling advantage.

2) Nobody in the field is nearly as rich as Mitt Romney, personally, or as well connected to a loyal base of similarly wealthy donors. Jeb Bush is rich, too, and will have plenty of donor money, but in pure dollar terms, he will be outmatched.

3) Almost all of Romney’s vulnerabilities are old hat. Bush’s are either recently discovered or yet to be revealed.

4) Romney’s one huge vulnerability—that he led the party to defeat in 2012—can be easily exploited with a call to turn the page by anyone who isn’t George W. Bush’s brother.

5) Romney and his team can be vicious. Certainly the Bush family is no stranger to vicious politics, but Jeb and George W. are different people with different demeanors and different teams. Romney throws hard punches. Bush could prove to be glass-jawed, weak-armed, or both.

6) Romney’s changing colors are generally considered a liability, but this cycle, they paint a path of least resistance for the Republican Party. Bush has admirably contended that he’ll be willing to lose the primary to win the general election. This has been taken both as a subtle jab at Romney, who swung way to the right during the primary in 2012, and as an indication that Bush will take heterodox stances on issues like education and immigration to preseve his general election viability. Romney, by contrast, offers an approach near and dear to the GOP’s heart: correctly identifying a national challenge, and prescribing the same remedy—tax cuts, lower social spending, deregulation—no matter what it is, preferably alluding to Reagan somehow along the way. He has opened the doors to the quiet rooms to which he once banished all discussion of income inequality, and now blames Obama for that very malady in public. His solution? “The best way to lower the tax burden on all American families is straightforward: lower rates and simplify the tax code.” The “Reagan” is silent.

Taken together, I think it’s pretty obvious that Romney would draw more blood from Bush than the other way around. But that doesn’t mean Romney wouldn’t sustain enough damage to sacrifice his lead to someone else. If the establishment were more formidable in GOP politics, Bush and Romney could create a temporary alliance, split the vote, and each retain a large enough share of it to wipe the floor with everyone else. In the real world, Bush is polling just one to three points ahead of Ben Carson. And we know where he’ll direct his fire if he starts to slip.